1. Field of the Invention
The present invention relates to apparatus for rapidly heating and cooling a mold for forming, molding or welding thermoplastic tubing and, more particularly, to a translatable spool circumscribing the mold and having a radio frequency (RF) energized heating coil to inductively heat the mold and to a manifold for directing cooling air between the mold and the spool.
2. Description of Related Prior Art
Molds used for heating, shaping molding and welding plastic tubing have employed a resistive element associated with the mold and tubing to be formed is disposed therewithin. Inductive heating of the mold has also been employed. Such heating has been at a fixed location on the mold without the capability of varying the location of application of the heat.
Cooling of molds used for forming, molding and welding tubing are cooled primarily through the use of massive heat sinks. The rate of cooling of the mold to permit withdrawal of the formed tubing is a function of the ambient temperature and the massiveness of the heat sinks. Furthermore, some benefit has been achieved through dissipation of heat by radiation from the heat sinks. Nevertheless, a significant time period is required to achieve the requisite cooling of the mold to permit withdrawal of the formed tubing. Such time constraints negatively impact throughput of the mold.
Prior art molds for use in conjunction with the forming, molding and welding of tubing are in the nature of a composite or unitary assembly having the requisite parts associated with one another to form a unit. If a different mold is to be used to achieve a different operation of forming, molding and/or welding of the tubing, a new unit must be constructed. Without the capability of using substitutable subassemblies related to the mold itself, significant costs are incurred by having to develop a complete unit for each type of operation to be achieved.